Weather Terms RVers Need to Know

All the winter storm advisories, alerts, watches, and warnings that we’ll soon start seeing can be confusing. The National Weather Service does a great job of disseminating weather predictions but sometimes it can be hard to know just what is what.

In the year 350 B.C., the Greek philosopher Aristotle gave one of the earliest descriptions of weather patterns in a text called Meteorologica. It included some of mankind’s first attempts to observe and record natural phenomena like water evaporation and earthquakes. Although it was a far cry from the Weather Channel, Meteorologica was the start of something that had eluded human beings for time immemorial: the ability to understand—and even predict—the weather.

Modern weather forecasting is a $7 billion-a-year industry—and for good reason. Despite all the advanced technology of modern society, humans are still pretty much at the mercy of the elements. America’s GDP can fluctuate by more than $1.34 trillion depending on the weather. In 2020 alone, more than 60,000 weather events killed 585 people in the United States and injured more than 1,700 more with flash floods, tropical storms, heat, tornadoes, ice storms, and thunderstorms doing most of the damage.

Weather forecasters are easy targets because, like football referees, people tend to take notice only when they get it wrong. The reality, however, is that meteorologists are right in astonishing percentages. When weathermen and women issue seven-day forecasts, they’re accurate about 80 percent of the time—90 percent for five-day forecasts.

If someone had told Aristotle that human beings would one day be able to accurately predict the weather nine times out of 10, five days in advance, he likely would have laughed at their overactive imagination.

It’s important to note that climate and weather are not interchangeable terms. Weather describes the short-term—day-to-day and hour-to-hour—state of the atmosphere including temperature, precipitation, wind, and visibility. Climate, on the other hand, measures average weather patterns over several decades.

I used a variety of scientific sources to compile this list of common weather terms that RVers should know and understand.

Coachella Valley, California © Rex Vogel, all rights reserved

Atmospheric pressure

Humans inhabit the very bottom of the Earth’s atmosphere and everything above creates atmospheric pressure. High-pressure systems form when downward pressure creates a clockwise air rotation, unlike low-pressure systems which generate counter-clockwise rotation. Both phenomena which are measured with barometers are critical to predicting weather events.

Black ice

Vehicle accidents are the leading cause of winter-related fatalities so when a meteorologist warns about the potential for black ice drivers should take it seriously. Black ice gets its name because it’s so thin that it’s nearly invisible on the road surface but the ice itself isn’t black. Black ice forms when sudden temperature increases causing snow to melt and drip onto roadways that are still cold enough to make the liquid water freeze on contact.

Blizzard

Not just any big snowstorm qualifies as a blizzard. A storm must meet three criteria to earn the harshest classification in winter weather. Blizzards have frequent wind gusts of at least 35 mph, sustained falling or blowing snow that reduces visibility to less than a quarter-mile, and these conditions are maintained for at least three consecutive hours.

Breezy and windy

The terms windy and breezy are sometimes used interchangeably but they don’t describe the same phenomenon. Breezy conditions involve air moving between 12 and 22 mph during pleasant conditions. Windy days, on the other hand, involve stronger winds up to 50 mph during stormy or inclement weather.

Dew point

The dew point represents the temperature to which air would have to be cooled to reach a level of moisture saturation. When it reaches the dew point, droplets of water or dew begin to form on solid objects like grass and vehicles.

Drought

Most people know droughts result from an extended lack of precipitation and abnormally high temperatures but overpopulation and land overuse are contributing factors, too. Droughts are among the most destructive forces in nature—only hurricanes are more economically damaging to the United States.

Usery Mountain Regional Park, Mesa, Arizona © Rex Vogel, all rights reserved

El Niño

The opposing warm half of ENSO is called El Niño (The Boy) which occurs irregularly every two to seven years and is often followed closely by a La Niña (see below) pattern. It warms the oceans and creates the opposite effect in terms of not just ocean temperatures but atmospheric pressure. It, too, is associated with irregular and sometimes severe weather patterns.

Flash flood

Flash flooding occurs when large amounts of water from sudden torrential rains—or occasionally an incident like the breaking of a dam—gushes through a narrow area that isn’t capable of absorbing high volumes of water. In many cases, flash floods which can roll cars and destroy houses happen in the immediate aftermath of extended droughts where parched land can’t absorb the influx of water quickly enough.

Flood crest

Flooding is one of the deadliest and most destructive weather phenomena in the country and on the planet. Weather professionals use specific terminology to describe rivers as they rise from excess water. A flood crest is the peak—the highest level the water will rise—which is the most significant and dangerous time of a flood but also an indication that the flood will soon recede.

Freezing rain

Freezing rain is formed through the same general process that creates sleet (see below) but they’re not the same thing. Sleet falls to the ground as ice. Freezing rain, on the other hand, remains in liquid form until it hits a cold object and then instantly freezes on contact.

Frost

Gardeners make their plans according to the first and last frost schedules in their respective agricultural zones. The frozen version of dew, frost occurs when cold, moisture-soaked air deposits water that freezes and leaves an icy film on things like plants and car windows.

Hail

Unlike sleet (see below) which is ice formed by rain falling through very cold air, hail is a much more dangerous phenomenon associated with much more dangerous weather. Hail forms when powerful updrafts inside of thunderstorms force water well above the freezing level. That water freezes into large hailstones which eventually become too heavy for the updraft and come crashing down to Earth.

Daytona Beach, Florida © Rex Vogel, all rights reserved

Haze

The dreaded three H’s are hazy, hot, and humid. Hot is self-explanatory, humidity deals with the level of moisture in the air but what exactly does it mean to be hazy? A haze can look like a thin fog but it isn’t caused by precipitation. Hazy conditions occur when large amounts of fine, dry particulate matter like dirt are suspended in the air which scatters light and gives the lower atmosphere a cloudy appearance.

Heat index

The heat index is essentially the same thing as the wind chill factor (see below) but for the opposite sensation of environmental exposure. It represents how hot the temperature feels when humidity is considered. The more humid the air, the less perspiration can evaporate which cripples the human body’s cooling system and makes it feel hotter when it’s humid outside.

Heat wave

Heat waves are long periods of abnormally warm weather. To qualify as a heat wave, it must last for at least two days and consist of temperatures that are outside the region’s historical average.

Ice storm

Ice storms are extended episodes of freezing rain that occur when precipitation falls in liquid form and freezes on contact. It becomes an ice storm when a quarter-inch or more of ice accumulates creating dangerous conditions. Ice storms which can be deadly and cause a lasting impact can add 500 pounds to the weight of power lines and increase the weight of tree limbs by a multiplier of 30.

Jet stream

Jet streams are thin but intense winds in the highest reaches of the atmosphere. Following the boundaries of cold and warm air, jet streams blow west to east although their flow sometimes shifts to north and south. Not only do these rivers of air affect global weather and help meteorologists identify atmospheric patterns but they’re crucial to air travel as flying into and out of them can dramatically affect fuel consumption and flight time.

La Niña

One half of the El Nino-Southern Oscillation (ENSO) phenomenon, La Niña (The Girl) is a global weather pattern that describes a dramatic cooling of ocean temperatures in the Western Hemisphere. La Niña is known for its disruptive impact on weather specifically heavy rainfall and an increase in low-pressure systems.

Okefenokee, Georgia © Rex Vogel, all rights reserved

Microburst

Microbursts are among the most dangerous and unpredictable weather phenomena on Earth and they form inside of already-dangerous thunderstorms. Updrafts—columns of rapidly rising air—sometimes suspend large amounts of rain and ice and when the updraft weakens, there’s nothing left to hold all that water and ice in place. That leads to a massive downdraft which sends the core of the column crashing to the ground and, upon impact, bursting out in all directions, leading to tornado-like winds, pressure, and destruction.

Nor’easter

Nor’easters are major, dangerous storms that are exclusive to the Northeastern United States. Geography, however, is not where these storms get their name. Nor’easters are named for the direction in which the storm’s most intense winds blow. Those winds are usually severe and they’re known to bring rain and snow and cause flooding and storm surges.

Polar vortex

The menacing phrase polar vortex is a relatively new term for winter weather forecasting but meteorologists have understood it as a concept for decades. A polar vortex occurs when a large section of very cold air, usually the coldest in the entire northern hemisphere, is pushed down the North American continent as far south as the Midwestern and Northeastern United States.

Relative humidity

Relative humidity is closely related to dew point (see above) but the two terms are not interchangeable. This term describes the amount of atmospheric moisture that exists relative to the amount that would exist if the air was saturated.

Severe thunderstorm

There are garden-variety thunderstorms and severe thunderstorms and when meteorologists mention the latter, the public should take it seriously. To be classified as severe, thunderstorms must include two potentially deadly elements: winds of at least 58 mph and hail at least one inch in diameter.

Sleet

One of the more unpleasant precipitation events associated with winter is sleet which stings the skin and turns roads and sidewalks into ice-skating rinks. Sleet graces the world with its presence when rain or melted snow freezes and turns into ice on its way from the sky to the ground.

Bernheim Forest, Kentucky © Rex Vogel, all rights reserved

Storm surge

It’s common to hear meteorologists warn that storm surge is one of the deadliest and most dangerous parts of major weather events like hurricanes. The phenomenon occurs when significant storms cause an abnormal rise in seawater above the limits of the astronomical tide. Storm surges can cause rapid, significant, and deadly flooding in coastal regions.

Tropical depression

Before a weather event graduates into a tropical storm, it’s a tropical depression. The infant stage of a hurricane, a tropical depression is a tropical cyclone with maximum sustained winds up to 38 mph.

Tropical storm

People sometimes use the terms tropical storm and hurricane interchangeably but one is an evolution of the other. Tropical storms form in the same places and under the same conditions as hurricanes but they achieve maximum sustained wind of just 39–73 mph. If a tropical storm’s maximum sustained winds hit 74 mph, it becomes a hurricane.

Watches and warnings

Meteorologists issue precautions to inform residents about the likelihood of serious and fast-moving weather events like tornadoes and severe thunderstorms. Watches are less serious and indicate that conditions are present for the formation of a severe weather event. Warnings, on the other hand, indicate that an event has been identified by a person or radar, a tornado or thunderstorm is imminent and to seek shelter immediately.

Wind chill

Everyone in North America north of a certain latitude knows there are two temperatures they have to consider when getting dressed in the morning in winter—the actual temperature reading and the one that counts: the wind chill factor. Also known as the feels-like temperature, wind chill represents how cold the weather feels on human skin when the chilling effect of the wind is taken into consideration.

Avery Island, Louisiana © Rex Vogel, all rights reserved

Wintry mix

Two words cold-weather commuters never want to hear are a wintry mix. When precipitation travels through an above-freezing warm layer of air followed by a cold, below-freezing layer, snow, sleet, and freezing rain can fall simultaneously.

Since we’re talking weather, here are a few related articles:

Worth Pondering…

In the spring, I have counted 136 different kinds of weather inside of 24 hours.

—Mark Twain (1835-1910)

New Airborne Radar Could Be a Game-Changer for Forecasting Hurricanes

The start of June marks the start of hurricane season in the Atlantic

June 1 marks the start of the 2023 Atlantic Hurricane Season which extends through November 30. The National Oceanic and Atmospheric Administration’s (NOAA) seasonal outlook predicts another active, yet near-normal Atlantic hurricane season with 12-17 named storms forecasted, 1-4 becoming major hurricanes. According to the National Hurricane Center, 2022 had only two major hurricanes but was considered one of the costliest seasons on record.

Goose Island State Park, Texas, following Hurricane Harvey (August 25, 2017) © Rex Vogel, all rights reserved

But experts have noted this season comes with a high level of uncertainty based on a developing El Niño and an unusually warm Atlantic Basin. Strong westerly winds spurred on by El Niño—a natural climate pattern marked by warmer-than-average Pacific Ocean water—tend to prevent nascent Atlantic storms from developing. This occurs because those increased upper-level winds can tear apart hurricanes as they try to form.

NOAA’s National Hurricane Center provides tropical storm and hurricane forecasts and warnings to help mitigate the impact of large storms. Recent technological advances have also helped the cause like the GOES-16 satellite. This satellite makes it possible to see hurricanes and other storms in their formative stages which help weather forecasters stay up to date.

The National Weather Service has invested substantially in supercomputing to gain three-fold processing power in turn reducing storm tracking and location error rates.

Goose Island State Park, Texas, following Hurricane Harvey (August 25, 2017) © Rex Vogel, all rights reserved

With the capability to fly over severe weather and achieve high altitudes for up to 30 hours straight, intelligence gathered by Northrop Grumman’s Global Hawk UAV has helped civilian authorities assess storm strength and direction and plan next steps for warnings and disaster relief. In partnership with NASA and NOAA, the Global Hawk UAV has been used to track hurricane intensification.

Next-generation radar technology capable of taking 3D slices of hurricanes and other storms is poised to move ahead after years of fits and starts.

Rockport-Fulton, Texas, following Hurricane Harvey (August 25, 2017) © Rex Vogel, all rights reserved

Driving the news: The National Science Foundation (NSF) announced $91.8 million in funding on June 1— the first day of the Atlantic hurricane season—for the National Center for Atmospheric Research (NCAR) to design, build, and test airborne phased array radar.

The technology consists of thousands of transmitters and receivers on horizontal plates mounted at different points on a plane.

Together, they would scan storms in unprecedented detail from storms’ overall organization to the type, shape, and direction of movement of droplets within the clouds.

Rockport-Fulton, Texas, following Hurricane Harvey (August 25, 2017) © Rex Vogel, all rights reserved

Why it matters: Currently, NOAA’s aging hurricane research aircraft fly tail-mounted Doppler radars into the heart of hurricanes. But the new APAR could yield significant insights into weather predictions and climate projections.

For example, it could provide a far more detailed picture of the inner structure of a hurricane. The data can then be fed into computer models to warn of sudden intensity changes and track shifts.

Rockport-Fulton, Texas, following Hurricane Harvey (August 25, 2017) © Rex Vogel, all rights reserved

Context: Hurricanes are churning out more rainfall than they used to. The storms are more likely to rapidly intensify with several landfalling systems in recent years leaping multiple categories on the Saffir Simpson Scale in just 24 to 36 hours.

In September 2022, Hurricane Ian suddenly jumped from a Category 3 storm to almost a Category 5. It used to be rare for storms to keep strengthening until landfall let alone do so rapidly. Now it is not. Such an intensity leap was made possible by warm ocean temperatures and abundant atmospheric moisture.

During the past several years, there have been multiple storms that rapidly intensified as they neared the Gulf Coast and did so through landfall. Previously, tropical storms and hurricanes tended to weaken as they neared the northern Gulf Coast in particular falling victim to cooler waters or stronger jet stream winds.

But that did not happen with Hurricanes Laura or Ida in 2020 and 2021—or with Hurricane Michael which ramped all the way up to a Category 5 storm in the Florida Panhandle in 2018.

This technology may also be able to improve understanding of these weather phenomena.

Goose Island State Park, Texas, following Hurricane Harvey (August 25, 2017) © Rex Vogel, all rights reserved

Zoom in: The funding will be used for a radar-outfitted C-130 research aircraft operated jointly by NSF and NCAR.

NCAR director Everette Joseph said the radar should be ready for use in 2028.

In addition to the NCAR research radar, NOAA is planning to buy a new fleet of C-130 hurricane hunters and outfit them with APAR units. It aims to have them flying in 2030.

The NSF investment does not cover NOAA’s new equipment though the oceans and atmosphere agency would benefit from NCAR’s research insights.

Rockport-Fulton, Texas, following Hurricane Harvey (August 25, 2017) © Rex Vogel, all rights reserved

Between the lines: In selecting NCAR for the funding and research, the NSF is following a long-established model with the Boulder, Colorado-based organization.

The partnership has helped advance weather and climate forecasting for decades.

However, NCAR has hit turbulence recently. Last week, NCAR and NSF announced a temporary suspension of flight operations at its research aviation facility at Rocky Mountain Municipal Airport which would be integrally involved in the APAR project.

An NSF spokesperson told Axios the reason for the stand-down was the “discovery of several lapses related to the safety management systems” at the facility.

“NCAR has done an initial analysis and does not expect any impacts on APAR from the safety stand-down at this time,” the spokesperson said.

Currently, a third-party review is taking place “to review NCAR’s aviation processes, culture, communication, and organizational structure,” the NSF said, projecting a return to full flight operations in the fall.

NCAR and the related University Corporation for Atmospheric Research are also trying to find more pilots in the wake of pandemic-related shutdowns and retirements, NSF stated.

Rockport-Fulton, Texas, following Hurricane Harvey (August 25, 2017) © Rex Vogel, all rights reserved

What they’re saying: APAR has been a priority for storm researchers and forecasters for years but is only now poised for flight.

Scott Rayder, a former NOAA chief of staff who now leads Leidos’ climate, energy, and environment activities said such technological leaps should not take so long given that lives are at stake with severe storms.

“When I first heard about the technology in 2012 I knew APAR would be a game changer,” Rayder told Axios. “The fact that it took 10 years to get to this decision is a concern—we need to find ways to more rapidly develop technologies like APAR and move them into operations.”

Go deeper

Stay safe out there!

Worth Pondering…

In reality, you don’t ever change the hurricane. You just learn how to stay out of its path.     

—Jodi Picoult

Are You Ready? The Hurricane Season is Just Starting

The tropics are heating back up

Will Grace top Elsa as the headliner storm of the season, even though Elsa was more than a month ago when the tropics were just beginning to stir?

As the remnants of Tropical Storm Fred degenerated into a tropical wave and its path swung further west into the Gulf of Mexico this past Saturday (August 14, 2021), Southwest Florida already had its eyes set on a new threat. The overnight formation of Tropical Storm Grace marked the second storm in a week the area has to monitor. The storm could make landfall in Florida by the end of the week, according to the National Hurricane Center.

Amelia Island, Florida © Rex Vogel, all rights reserved

August is when the tropics typically fire up. But we aren’t there just yet. Dr. William “Bill” Gray (1929-2016), regarded as a pioneer in the science of hurricane forecasting, would literally ring a bell on August 20 to announce the real start of hurricane season. That’s several days out.

There is definitely something that “clicks” in late August allowing for tropical systems to shift from mostly rainmakers (in some cases, these are still catastrophic) to extreme wind makers. Wind damage and deaths due to storm surge could jump dramatically in the weeks ahead.

Cedar Creek, Florida © Rex Vogel, all rights reserved

Here’s the good news: Fred was not one of those storms (and at the time of writing it’s too early to know about Grace). And that’s actually a little bit surprising considering that storm names beginning with the letter “F” are the second most likely names to be retired, meaning they were particularly deadly or destructive.

Here’s a breakdown of retired hurricane names categorized by the letter:

Letter of the alphabet             Number of retired storm names

A                                 7

Agnes, Alicia, Allen, Allison, Andrew, Anita, Audrey

Crystal River, Florida © Rex Vogel, all rights reserved

B                                 3

Betsy, Beulah, Bob

C                                 9

Camille, Carla, Carmen, Carol, Celia, Cesar, Charley, Cleo, Connie

D                                 8

David, Dean, Dennis, Diana, Diane, Donna, Dora, Dorian

E                                  5

Edna, Elena, Eloise, Erika, Eta

Daytona Beach, Florida © Rex Vogel, all rights reserved

F                                  9

Fabian, Felix, Fifi, Flora, Florence, Floyd, Fran, Frances, Frederic

G                                 5

Georges, Gilbert, Gloria, Greta, Gustav

H                                 6

Harvey, Hattie, Hazel, Hilda, Hortense, Hugo

I                                   12

Igor, Ike, Inez, Ingrid, Ione, Iota, Irene, Iris, Irma, Isabel, Isisdore, Ivan

Venice, Florida © Rex Vogel, all rights reserved

J                                  5

Janet, Jeanne, Joan, Joaquin, Juan

K                                 3

Katrina, Keith, Klaus

L                                  4

Laura, Lenny, Lili, Luis

M                                6

Maria, Marilyn, Matthew, Michael, Michelle, Mitch

Rockport-Fulton, Texas following Hurricane Harvey, a Cat 4 hurricane (August 25, 2017) © Rex Vogel, all rights reserved

N                                 2

Nate, Noel

O                                 2

Opal, Otto

P                                  1

Paloma

Rockport-Fulton, Texas following Hurricane Harvey, a Cat 4 hurricane (August 25, 2017) © Rex Vogel, all rights reserved

R                                 2

Rita, Roxanne

S                                  2

Sandy, Stan

T                                  1

Tomas

W                                1

Wilma

Goose Island State Park, Texas following Hurricane Harvey, a Cat 4 hurricane (August 25, 2017) © Rex Vogel, all rights reserved

No, that’s not a typo. Believe it or not, the letter “I” is responsible for the most retired hurricane names. According to the Weather Authority at News 4 JAX, the best guess this year is that we’ll see the “I” storm sometime shortly after Labor Day. That would be near the peak of hurricane season which is September 10.

Ida will be this year’s “I” storm.

But which storm will be this year’s strongest? Possibly, Julian. It doesn’t sound particularly intimidating (none of them does, really), but that’s as good a guess as any. And again, that’s purely a guess.

The Big Tree at Goose Island State Park, Texas stood firm during Hurricane Harvey, a Cat 4 hurricane (August 25, 2017). Your RV would not be this fortunate. © Rex Vogel, all rights reserved

Dr. Klotzbach, the lead CSU forecaster, recently updated his seasonal hurricane forecast. He’s now expecting us to see four major hurricanes. In other words, the weeks ahead are likely to be very challenging for many people.

Worth Pondering…

Hurricane season brings a humbling reminder that, despite our technologies, most of nature remains unpredictable.

—Diane Ackerman